Method of crown shaving gears



Feb. 20, 1951 w. s. PRAEG METHOD OF CROWN SHAVING GEARS 9 Sheets-Sheet 1 Filed July 21, 1947 INVENTOR.

WALTER s. PRAEG FIG. I.

Feb. 20, 1951 w. s. PRAEG METHOD OF CROWN SHAVING GEARS 9 Sheets-Sheet 2 Filed July 21, 1947 .r Ir. 1.

INVENTOR. WALT-ER s. PRAEG W-W Y 15 7 ATTORNEYS Feb. 20, 1951 w. s. PRAEG 7 METHOD OF CROWN SHAVING GEARS Filed July 21, 1947 9 Sheets-Sheet 5 INVENTOR.

WALTER S. P RAEG ATTORNEYS Feb. 20, 1951 w. s. PRAEG 2,542,569

METHOD OF CROWN SHAVING GEARS ATTORNEYS Feb. 20, 1951 w. s. PRAEG METHOD OF CROWN SHAVING GEARS 9 Sheets-Sheet 5 Filed July 21, 1947 INVENTOR.

WALTER s. PRAEG ATTORNEYS Feb. 20, 1951 w. s. PRAEG METHOD OF CROWN SHAVING GEARS 9 Sheets-Sheet 6 Filed July 21, 1947 INVENTOR. WALTER S. PRAEG MON r W fi g f w @E OMN z N mmm wow 22m \\r Jmm wqwwmm R II fl TU NU/ @ON NON mwwfi/ mNN x I s ma @NN KN T s Y E N R O n A W. S. PRAEG METHOD OF CROWN SHAVING GEARS Feb. 20, 1951 9 Sheets-Sheet 7 Filed July 21, 1947 INVENTOR.

WALTER S. PRAEG ATTORNEYS Feb. 20, 1951 w. s. PRAEG 2,542,569

METHOD OF CROWN SHAVING GEARS Filed July 21, 1947 9 Sheets-Sheet 8 FIG-l3- INVENTOR. WALTER S PRAEG BY W .F ATTORNFYS Feb. 20,. 1951 w. s. PRAEG METHOD OF CROWN SHAVING GEARS 9 Sheets-Sheet 9 Filed July 21, 1947 ,a'rs 1 7 377 385 -379/ 372 as: E

FIGJS.

388 FBGQ |8- INVENTOR.

WALTER S.PRAEG ATTORNEYS LI LL LJ Patented Feb. 20, 1951 METHOD OF CROWN SHAVIN G GEARS Walter S. Praeg, Detroit, Mich., assignor to National Broach & Machine Company,'Detroit, Mich., a corporation of Michigan Application J uly21, 1947, Serial No. 7 62,413 '4 Claims. (01. 90-1.6)

The present invention relates to apparatus for and a method of crown shaving gears employing diagonal traverse. a

It is an object of the present invention to provide a method of crown shaving gears in which a gear and gear-like tool are driven in meshing relation with their axes crossed While at the same time the gear and tool are relatively traversed in a plane parallel to the axes of both said gear and tool and in a direction in said plane making a substantial angle with the axis of the gear, and in which a relative rocking motion is provided between the gear and tool in timed relation with respect to traverse.

It is a further object of the present'invention to provide the relative rocking aforesaid such that displacement takes place equally in opposite directions from a central neutral position and reaches a maximum adjacent either end of the traverse stroke, and in which final'completion of the traverse stroke is accompanied by a relatively rapid reverse rocking to position the axes of the gear and tool in substantially the neutral position.

It is a further object of the present invention to provide apparatus for crowning gears by di agonal traverse crossed axes shaving in which motion multiplying means are provided operable in accordance with traverse to effect relatively rapid crowning.

It is a further object of the present invention to provide a gear crowning machine of the type described including interconnected traverse and camming means.

It is a further object of the present invention to provide a gear crowning machine of the character described having a feed screw for effecting relative traverse between a gear and tool and a camming screw driven in timed relation to the feed screw to impart relative motion between two elements of a camming device.

It is a further object of the present invention to provide a gear crowning machine in which means are provided for angularly adjusting the direction of relative traverse between a gear and tool in combination with camming means for providing a relative rocking motion between gear and tool including connections operable in all positions of relative adjustment aforesaid to carry out the crowning motion.

Other objects and features of the invention will become apparent as the description proceeds, especially when considered in conjunction with the accompanying drawings, wherein:

, tion, of a modified knee construction of the ma Figure '1 is a front elevation of a gear finishing machine constructed in accordance with the present invention;

Figure 2 is an end elevation of the knee and tables of said machine;

Figure 3 is a fragmentary front elevation of the knee and tables shown in Figure 2, partly in section;

Figure 4 is an exploded perspective view of the camming mechanism of the machine shown in Figures 1 to 3;

Figure 5 is a front elevation, partly in secchine shown in Figure 1;

Figure 6 is a fragmentary end elevation of the camming structure incorporated in the knee illustrated in Figure 5;

Figure '7 is a plan elevation of a modified knee construction which may be substituted for the knee illustrated in Figure 1;

Figure 8 is a front elevation of the knee shown in Figure 7, with parts sectioned along the line 88 of Figure 7;

Figure 9 is a detail view illustrating a modified cam construction;

Figure 10 is an end elevation of the knee illustrated in Figures 7 and 8;

Figure 11 is a fragmentary section on the line lll| of Figure 8;

Figure 12 is a fragmentary section on the line l2-l2 of Figure 8;

Figure 13 is a fragmentary plan view of a modified gear crowning machine;

Figure 14 is a side elevation of the rocking table shown in Figure 13;

Figure 15 is a fragmentary section on the line iii-l5 of Figure 14;

Figure 16 is a fragmentary end elevation of another embodiment of the invention;

Figure 17 is a horizontal plan view of the rocking table; and c Figure 18 is a fragmentary view of the rocking table alone.

Referring now to Figure 1, there is illustrated a gear shaving machine comprising a main casting or frame H3 having a forwardly projecting overhanging part H from which depends a tool supporting head I2 supporting and driving a rotary gear finishing tool T. The head I2 is angularly ad ustable about a vertical axis and includes driving connections (not shown) by means of which the tool T may be positively rotated in difierent angular positions of adjustment of the head I2.

Frojecting forwardly adjacent the bottom of 3 the frame H3 is a platform 28 above which is mounted for vertical adjustment a knee 2 l, vertical adjustment of the knee 2! being effected by an adjusting screw 22. At the top of the knee 2i is an outer table 25 to which is pivoted a rocking or crowning table 26, the pivot support for the rocking table 26 being indicated at 21.. Tables 25 and 28 are provided with means whereby they may be traversed in any direction in a horizontal plane, and these means include a lower plate 33 which is adjustable about a vertical axis. The plate 39 is formed to provide ways '32 therein in which is slidably mounted a second plate 33. The

outer table 25 is connected to the upper plate 33 for relative angular adjustment about a vertical axis, and preferably the table 26 is provided with means preserving the orientation of said table,

whereby plates 33 and 3-3 may be angularly adjustable as a unit with respect to the knee 2! and the table 25. The plates 30 and 33 which have the rectilinear ways 32 therebetween may be referred to as anadjustable "sandwich for adjusting the direction of traverse of the tables 25 and'26.

Mounted on the rocking table'2'5'are a pair of work supporting heads 35 and 36 which are adapted tosu'pport -a work piece W'for rotation therebetween. In Figure 1, for simplicity the axes'of'the work piece W and tool T have been shown as parallel, but inpractice these axes will be adjusted to cross at a limited angle so as to carry out the operation known in the 'art crossed axes gear finishing. 7

Means are provided in thekn'ee 2| for effecting a slow traverse of the table 25 and hence the table 25 in a horizontal plane, and other means indicated generally at 4B are provided for rocking the table 28 in timed relation to the relative traverse. v p 7 V In Figures 2 130 4 there is illustrated in detail a construction of knee and a camming device for effecting rocking of the table28. Referring now to these figures, the upper plate -33 "is-provided with a depending feed nut A vhich has associated therewith a feed screw 43 rigidly supported by the lower plate '39., The feed screw 66 has a bevel gear ill thereon which meshes with a bevel gear carriedby the verti'cal'shaft in the knee (not shown). 7 The axis of this shaftis coincidental with'the vertical axis about which the plate 38 is adjustable, and accordingly angular adjustment of the plate 32 about its vertical axis is permitted without disturbing the meshing engagement between the gear 4 andits driver.

The outer table 25 is angularly adjustable about a vertical axis on the upper plate 33, and has for this purpose a central pilot 48 fitting into an opening in the top plate 33. Clamping bolts 49 are provided by means of which the table may be rigidly clamped'to' the uppel'fplate' 33 after adjustment has been accomplished. Preferably a linkage construction, indicated generally at EE, is providedfor preserving the orientation of the table 25 during angular adjustment of the sandwich comprised by the plates 3!) and 33.

The rocking table 26 which carries the head and tailstocks'35 and 36 is mounted for rocking movement about the axis of the pin 21. Jack screws, indicated generally at M, are provided etween the outer table 25 and the rocking table 26 so that the rocking table may be rigidly supported against rocking movement on the outer table 25 when the crowning operation is not to be performed. It may also be mentioned that the jack screws '51 provide means for inclining 4 the rocking table a predetermined amount, if desired, whereby the gear finishing operation may produce slightly tapered gears. When the crown ing operation is to be carried out the jack screws 5! are discormected.

In order to provide a relative rocking motion between the rocking table 26 and the outer table 25, in timed relation to the relative traverse resulting from rotation of the feed screw 48, the camming means 46 is provided. The oamming means is best illustrated in Figure 4 and comprises a disk fiil mounted for adjustment about a vertical axis as by a clamping bolt 6!, indicia 62 being provided to indicate the angularity of adjustment. lllpstanding from the disk is an arm 63 having an opening therethrough for supporting a cam block 64, the cam block being adjustable about the axis of the opening and supported therein by a bolt-55. As best seen in Figure 4, the cam block 54 has a relatively deep slot 65 formed therein. The disk' 55 is adjustably sup ported on a bracketE'i which extends from one side of the knee 2}.

The outer table 25 is provided with a relatively large opening "it and the remaining portion of the camming device li) is secured to, the'underside of the rocking table 23 and projects downwardly'throughthe opening it This comprises a disk H which is angularlyadjustable with respect to the table 26 and is held in adjusted position by means of a supporting clamping bolt l2 "Projecting downwardly from the underside of the disk is a bifurcated block 13 providing arms #4 and "25 between which is pivotal-1y supported a block '16, this block being pivoted by pins l1 and 18 about a transverse horizontal axis. Extending through the "block 15 is a cam follower pin 8%] having a'fiattened front "portion 8! receivablein the slot 56. Inasmuch as the rocking of the table 26 always takes place about the axis of the pivot support 2?, this rocking motion therefore'talg'es place about an axis perpendicular to the axis of the worl; W. However, since the traverse of the tables 25 and Ziiwith respect to the knee 2| may take place inany direction in a horizontal plane, and preferably takes place in ,a directionmaking a, substantial angle with the axis ofthe work piece W, the swivel connections illustrated in J'Figure 4 are necessary to preserve the camming action during relative traverse without binding of the parts. It will be observed that adjustment of the disks H and 62 about their vertical axes may be effected simultaneously, and this adjustment is carried out to cause the slot 65 to extend in a plane parallel tothe direction of traverse of the table 25 as determined by the angular adjustment of the plates 35 and 33. Furthermore, the slot 66 is relatively deep, and cooperating portion Bl of the pin 8! extends to a substantial depth therein so that as traverse takes place the camming relationship between the slot 65 and the follower BI" may be preserved even though the follower BI is moved part way out of the slot 66. Binding of the 'follo wer' 8l and the slot 66 1s prevented by the swivel mounting provided for the block '16, as will readilybe apparent.

While the slotiiii is shown as extending recti linearly in the present modification, if desired other contours may be provided forthe slot, in which case it may -be desirable to provide the follower portion 8| of the pin 83 with a round contour. More specifically, and as described more in detail later, the slot-'68 may have end portions extending angularly with respect to the main central portion so that as traverse takes place rocking motion of the table 25 starts from a neutral horizontal position, rocks rapidly to a limiting inclined position, thereafter rocks slowly in a reverse direction through the inter mediate neutral position to an oppositely inclined limiting position, and if desired thereafter returns abruptly to a neutral horizontal position.

Referring now to Figures 5 and 6, there is shown another embodiment of apparatus. It will be understood that in this modification the remainder of the gear finishing machine is as illustratedin Figure l and that suitable head and tailstocks are mounted on the rocking table I25 which is pivotally supported on the outer table I25 by the pivot pin I21.

The method of finishing gears by diagonal traverse affords the possibility in many cases of finishing a gear from end to end with a relatively short traverse stroke, and in some cases this stroke may be so short that the relative traverse motion between the rocking table and the knee may be insufiicient to provide an efficient camming action. In the present modification means have been provided associated with the traversing mechanism for providing independent relative motion between two camming elements whereby the rocking motion of the table relative to its traverse may be as rapid as desired.

In this modification there is illustrated a gear IOI which is in a train of gears I62 which includes gears for driving a feed screw (not shown) identical with the feed screw 46 inthe modification previously described. Accordingly, the gear I! is driven in timed relation to the rotation of the feed screw and hence in timed relation to the relative traverse of the tables I25 and I2t.

A transmission support bracket IE2 is pro vided which is rotatable as a unit about the axis of the gear M and which carries a spline shaft Hi5 having a bevel gear I96 at its lower end meshing with a bevel gear I 01 rotatable with the gear Ifil. Extending upwardly from the bracket we is a rigid tube I98 on which is slidably mounted a housing sleeve I 99 extending from a main housing I Iii. The housing IIB supports a b'evel gear I I I keyed or otherwise secured to a splined sleeve H2 having non-rotatable but slidable engagement with the spline I55. The housing II I} also carries a bevel gear H4 mounted on a rotatable support H5 and having an internal splined formation slidably engaging a splined portion I it of a camming screw III.

The rocking table I has an outwardly and downwardly projecting arm I25 at one end from which projects a follower I2I slidable in a slot I22 carried by a. cam slide I23. The cam slide I23 is supported for sliding movement by plates I24 and I24 and includes an adjustable camming member I28 in which the slot I22 is formed. The camming member I23 is adjustable about a horizontal axis and maybe clamped in adjusted position by a clamping bolt I29. The cam slide I23 includes a recess I36 closed at one end by a removable feed nut I3I with which the camming screw III cooperates.

Rotation of the feed screw by the train of gears I82 results in timed rotation of the gear IIlI and hence of th bevel gears It! and I06, which in turn results in rotation of the camming screw III. Dependent therefore upon the lead of the threads of the camming screw III and the nut I3I, the cam slide I23 is caused to move longitudinally of the table I25 and thereby to effect rocking motion of the table through the medium slot I22 is illustrated as straight, but again it v preserving orientation of the tables 225 and 226' of the cam follower m carried by the arm lit and th slot I22 which may be inclined as desired. This mechanism provides means by which the rate of rocking may be relatively great as compared to the rate of relative traverse, and bya proper selection of change gears in the train I02 and/or the selection of the.lead of the camming screw III the rate of rocking may be predetermined.

In this illustrated construction the camming may have-reversely inclined end portions, as

will subsequently be described.

Referring now to Figures 7 to 12, there is illustrated yet another embodiment of the present invention. In this case the figures illustrate a modified knee construction which may be substituted in the complete machine illustrated in Figure 1 without modification of the other structure. i

In this embodiment the knee 22I carries a driving bevel gear 23! whose axis is vertical and which is adapted to mesh with a bevel gear 222 carried by the traversing feed screw 293. The fetd screw cooperates with a feed nut 22 depending from the upper slide plate 233 to effect relative traverse between the upper slide plate 233 and the lower slide plate 235?. Coaxial with the axis of the bevel gear 25% is a short shaft 2&5 carrying a bevel gear Zilt meshing with the bevel g-ar 202, and at its upper end carrying a bevel gear 26}? meshing with a bevel gear 298 carried by the camming screw 25! The outer table 225 carries an inner rocking or crowning table 226 which is pivoted thereto for rocking movement by a pin 227.

As best seen in Figure 7, the outer table 225 has a linkage, indicated generally at M2, for

during angular adjustment of the plates 23d and 233 so as to adjust the direction of traverse of the tables. The rocking table 223 is provided with work plates 215 in guiding contact with hardened guide elements 2I6 so as to prevent lateral movement of the table 225 during rocking movement thereof. The table is also provided with locking means indicated at 2 I I which retains the two tables in rigidly associated relation of rocking is not desired. A jack screw 2 I33 is also provided intermediate the tables 225 and 226 but is disconnected when the crowning operation is to be'performed.

Since the shaft 255 is concentric with the axis of the gear 2m, it will be appreciated that the sandwich comprised by the plates 23s and 233 may be rotated to adjust the direction of traverse of the tables without destroying the driving connection afiorded by the gears 2M, 2B2, 286, 231 and 208. It will also be observed that as illustrated the camming screw shaft 229 will be rotated at substantially greater speed than the traverse screw 203.

The outer table 225 is provided with a cam slide 255), it being supported thereon by plates 25I and 252, as best seen in Figure 12. The cam slide 255 is provided with a recess 253 adapted to be closed by a removable nut 254 which cooperates with the threads in the end of the camming screw 269. Rotation of the cam ming screw 209 therefore effects longitudinal movement of the cam slide 250. At its outer end the cam slide 259 is provided with an adjustabl head 255 having a slot 255 formed therein. The head 255 is adjustable about a horizontal estates axis and may be clamped in adjusted position bya clamping bolt 251.

The rocking table 225 has an overhanging arm 260 which projects downwardly into the neighborhood oi the head 255 and theresupports a pin having a flattened portion 251 which is received in the slot 255. The pin having the flattened portion l is adjustable about its axis so as to cause the flattened portion to properly enter and be guided by the slot 256.

Referring now to Figure 9, there is illustrated a modified form or cam slot. In the embodiments thus far specifically illustrated and described the cam slots 66, I22 and 256 have been straight. .Reference has been made to the fact that diagonal traverse sometimes requires rela tively rapid and relatively great rocking movement with respect to traverse. In some limiting cases this relative rocking motion may be so great that interference may result, or it may be impossible to bring the gear and gear-like tool into a condition of loose mesh at the end of a stroke as is desirable. Accordingly, in Figure 9 there is illustrated a cam 2'15 having a slot the central portion of which is straight, as indicated at 216, and the opposite ends of which are reversely inclined as illustrated at 271. This arrangement, given the proper selection of length of stroke and the proper relative crowning traverse between the camming elements of the machine, may result in the rocking table being in substantiallyhorizontal position at one end of the camming stroke. As traverse starts, the follower 218 which in this case will be round, causes a relatively abrupt rocking motion of the rocking table to a limiting position as determined by the adjustment of the cam. Thereafter traverse throughout the major portion of the stroke results in reverse rocking of the table, and at the mid position during the stroke (a condition illustrated in Figure 9) the follower 218 is in mid position in the straight portion 278 of the cam and the table 226 is in horizontal position. Further traverse to the end of the stroke results in further rocking of the table 226 in the same direction until it reaches a limiting position as determined by the cam setting, which normally will be such that the table is rocked an amount equal to but in opposite sense from its initial tilted position. Further traverse, if such is eifected, causes the cam follower to again enter the reversely inclined end portion 217 of the slot, which will cause the table to return toward horizontal position, thus introducing clearance between the teeth of the gear and tool.

The normal gear finishing operation as carried out with diagonal traverse is accomplished by an over and back reciprocation or traverse so that it is, strictly speaking, unnecessary to provide the reversely inclined portions at both ends of the cam 215. It is, however, highly desirableto have a reversely inclined portion at the end of the cam corresponding to the beginning of the stroke so that as the over and back traverse is completed. the rocking table assumes what approaches a horizontal position and clearance is introduced between the teeth of the gear and 'tool, thus facilitating unloadin of the finished gear and loading of a new gear to be finished.

It will of course be understood that the cam illustrated in Figure 9 is more or less diagrammatically illustrated and it is contemplated that if desired this cam may have adjustments pro vided thereon so that the reverse rocking at one or both ends of a stroke may begin after prede- 8 termined-traverse from the central neutral posit-ion. on the other hand, the ram 215 in all modifications thus far-describedis easily replaceable so 'that' it is entirelyfea'sible to provide a separate cam-for each crowning operation if such is desired.

Referring-now to-Figures 13,14 and 15, there is illustrated another embodiment of the present 'i'nvntionj In this case the outer table 325 is intended 'for reciprocation limited 'to' the direction of the arrow 3B! and it carries'a-rocking t-able'326 which is rockable about the axis of a pivot pm 321 carried by upstanding arms 328 carried "by adjustable support mounted onthe table 325. Inasmuch as the direction-of traverse is limited to the direction of the'arrow 3'0'l,-a djustment betweenthe direction of the traverse and the axis of a work "piece is effected by adjusting the support 346 an'gularly' about a vertical' air'is as determined by a central pilot 3B3. Therocking table 326 carries head's305 and 306 between' wh ich the work piece W' is mounted for free rotation. muss case a tool T is supported by an overhanging head precisely as in the embodiment of the invention illustrated in Figure 1. In fact, this embodiment of the invention may'be'considered as a case which the direction of the ways in which the table 325 is slidable is fixed to extend transversely across the fr'ontof the machine.

in order to effect substantial rocking of the rocking table 326 eventhough the relative traverse-in the direction of the arrow'30l is relatively slight, thefollowing mechanism is provided. cammingbracket 319 is mounted for rocking movement about a pivot pin 31! supported between a pair of cars, one of which is indicated at 312. .In order to accommodate different angular positions of adjustment of the rocking table 325, an actuating arm 313 is pivoted to the bracket 3m and is adapted to be locked in adjusted position by locking bolts 3M. The arm 313 has an elongated openin 315 which receives a pin'3l6 adjustable along a slotted member 3.

"As best seen in Figure 15, the rocking table 326'has depending camming elements 340 which are equally displaced laterally from the center thereof and which cooperate with slidable camming pins 34]. The pins 34! have inclined camming surfaces 342 and as the pins are moved inwardly and outwardly with respect to the camming portions 340 of the table 325 the table 326 is cause'dto rock. The pins 3M have heads 343 against which bear compression springs 344 received in recesses 345 formedin thesupporting structure 396.

Itwill be observed in Figure 13 that as the table 325 is traversed in .a direction parallel to thearrow 3B! the arm 313 will be caused to rock about its pivot point 3, thereby rocking the bracket 310 about the same point and moving one end of the bracket inwardly against one of the pins 34! while the other end of the bracket moves outwardly, permitting the other pin to move outwardly a correspondin amount under the influence of the compression spring 344.

It will be observed that the foregoing structure provides for relatively great rocking motion of the rocking table 326 in timed relation to traverse of the table 325 so that irrespective of how small the amount of traverse, a desired amount of rocking motion may be provided. In this case also it will of course be a simple mat ter to provide for the predetermined rocking motion described above in which the tableis'in approximately horizontal position at one end of the traverse and thereafter rocks to a predetermined maximum followed by a slow reverse 'rockin through neutral to a predetermined maximum in the other direction. This of course may be accomplished by suitable contouring of the camming element 34!, which will be apparent to those skilled in the art without further is a crowning; attachment including a rocking table 363, this table being mounted for rocking movement about a pivotal support 36! carried by upwardly projecting arms 352. The arms 332 are connected by a plate 363 which is angularly adjustable about a vertical axis with respect to the table 356. Mounted on the rocking table 360 is a tailstock 363 and a headstock 334 betwee which is mounted a work gear 335.

By virtue of the construction just described, the rocking table 353 may be angularly'adjusted about a vertical axis, together with the plate 333, to dispose its axis at any desired angle. At

the same time, the tool support 352 may be adjusted abouta vertical axis to dispose the axis of the tool 353 carried thereby at any desired angle. Suitable means are provided for traversing the table 335 in the direction of the arrow 37% in Figure 1'7, and accordingly a gear and gear lik tool may be meshed with their axes crossed at the appropriate angle to bring about meshing engagement and the direction of the axis of the gear may be disposed at a desired angle with respect to the direction of traverse as indicated by the arrow 37B. p

In order to effect rocking of the table 360 in accordance with the back and forth traverse of the table 355 camming mechanism is provided. This mechanism takes the form of a support 31! carried by the fixed knee of the machine from which extends a bracket 312 having a head 373 provided with a plurality of pin receiving openings 37d. Secured to the side of the plate 366 is a yoke 315 on which a block 31'! is movable about pivot aXis 313. An adjustable arm 318 having an elongated slot H9 is secured to the block 31'! and may be clamped in adjusted position thereon by bolts 380 or the like. A pin such as indicated at 38! is received in one of the pin receiving openings 3M and extends through the slot 319.

Secured to the upper surface of the plate 306 is a pivot arm 352 which is mounted for movement about a vertical pivot pin 383 carried by the plate 365. interconnecting the block 377 and the pivot arm 332 are a pair of links 385 by means of which the rocking movement of the block 311 about its pivot axis 3'35 is transmitted to the pivot arm 332, rocking it about its pivot axis 383. The pivotarm 332 is provided with an elongated slot 38'! which receives an upwardly projecting pin 383 carried by a longitudinally shiftable cam bar 396 having inclined camming elements 39l at each end thereof.

Accordingly, as the table.

356 is traversed in the direction of the arrow 370 a rocking motion is imparted first to the block by the cams 39l and therollers 332.

By virtue of the adjustability provided by the plurality of pin receiving holes 3 M, the amplitude of longitudinal movement of the cam 390 may be selected. Furthermore, the bracket 312 is preferably longitudinally adjustable in its support 3?! so that the head 313 thereof may be brought into proximity to the arm 3'58 in whatever position of adjustment the rocking table 360 may be.-

In use the arm 378 will be adjusted about its pivot connection 37% so that in mid position of the table 356, or in other words a position correponding to mid stroke of the table, the arm will be perpendicular to the direction of traverse, thus insuring equal rocking'movement in both directions from an intermediate neutral position in which the rocking table 350 is parallel to the traversing table 353. ii

For simplicity the tool head 352 and the rock,- ing table 360 have been shown in Figure 16 with the axes of the gear and tool parallel to the direction of traverse of the table 356. However, in use the rocking table will normally be swung around so that the axis of the gear being machined exinto proper meshing engagement with the teeth made to the operation as a shaving operation;

This implies the use of a shaving cutter of a type now familiar in the art which is in the form of a gear having grooves or serrations extending up and down the teeth of the cutter. The spaces between the grooves form guiding linesand the corners of these lines form cutting edges. In the operation of the machine the rotation of the gear and tool is at substantial speeds, such for example as between 200 and 1,000 surface feet per minute, and the relative traverse is relatively slow, such for example as between two and ten inches a minute. I

While the operation as described is preferably carried out by employing a shaving cutter of the type referred to, similar results may be obtained when the gear finishing tool is a lap rather than a shaving cutter. In this case the removal of metal depends upon the provision of abrasive particles between the teeth of the lap and the teeth of the gear, as is well understood in the art. Accordingly, where the invention is defined as gear finishing it is to be understood that both shaving and lapping are included.

The drawings and the foregoing specification constitute a description of several embodiments of the improved machine and method for crowding gears by diagonal traverse in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. The method of crown finishing gears which relativecrowning stroke between said members including relativev traverse in a direction which occupies a plane parallelto theaxes of said members and which is angularly related in said plane to the axes of said members, saidcrowning mo tion-comprising a rapid approach betweensaid members from loose mesh at one end of said stroke, a gradual separation, between said members terminating when the mid portion. of said gear teeth are being finished, a'gradual approach between said members as the finishing action approaches the ends of said gear teeth, and a rapidseparation between. said members at the end of said stroke, leaving the members ina condition of loose mesh.

2. The method of crown finishing gearswhich comprises rotating a gear member. and gear-like tool in mesh at crossed axes, and providing a 1 relative crowning stroke between said members including relativ traverse in a direction which occupies a plane parallel to the axes of said members and which is angularly related in said plane to the axes of said members, said crowning motion comprising a gradual separation between saidmembers as the finishing action of said tool is caused to progress from one end of said teeth toward the mid portion thereof, terminating when the mid portion of said gear teeth are being finished, a gradual approach between said members as the finishing action approaches the ends ,of said gear teeth, and a rapid separation between said membersatthe end of said stroke, leaving the members ina condition of loose mesh.

3. The method of crown finishing gears which comprises rotating a gear member and gearlike tool in mesh at crossed axes, and providing a relative crowning stroke between said members including relative traverse in a direction whichoccupies a plane parallel to theaxes; of said members and which is angularly-related in said plane to the axes of said members, said crowning motion comprising a relative. rocking motion between saidmembers intimedrelation to said traverse, said relative rocking motion comprising movement from a neutral position with the members in loose mesh to a maximum cutting position as one end ofthe teeth of said 12 second maximum cutting. position as, the other end ofsaid teeth are engaged, the relative motionsbeingretraced on the reverse stroke, Whereby thefinishing operation is'completed with the members inlo'ose mesh. 7 Y

4. The method oi, crown finishing gears :which comprises placinga gear member and gear-like toolmember in loose mesh at crossed axes with the teeth of said gear member meshedadjacent one endtl ereof preparatory to rectilinear relative traverse between said gear and tool members in adirection occupying a plane parallel to the axes of bothsaid gear and tool members, effecting a relative back and forth traverse in a direction angularly related to the axes of both gear and tool, and-providing a sequence of relative rockingmotion between said gear and tool members in timedrelation to said traverse which comprises aninitial quick rocking motion to displace the axis of one of said members a maximum amount from parallelism with said plane to initiate a relatively deep out at said one end of said gear teeth, a comparatively slow rocking motion in the reverse direction causing the axis of said one member to pass through parallelism with said plane as themid portions of the gear teeth are machined to'a position in which the axis of said one, member is displaced from parallelism with said plane in the opposite sense as the other end of said gear teeth are machined, and during reverse traverse retracing said relative rocking movement to terminate traverse and rocking with said gear and tool in loose mesh.

WALTER S. PRAEG.

REFERENCES CITED Therfollowing references are of record in the file of this patent:

UNITED STATES PATENTS 

